The present invention relates generally to plant growth regulation, and in particular to plant growth regulation utilizing combinations of active agents that each inhibit plant gibberellin biosynthesis.
As further background, agents that accelerate or retard the rate of growth of plants have been known and used in the field of turfgrass and other plant management. Agents that retard or inhibit shoot, stem and leaf elongation have traditionally been categorized by four modes of action. A first mode involves the inhibition of mitosis in the meristematic tissue which halts cell division and elongation. A second mode involves a reduction of cell elongation by inhibiting or retarding gibberellin synthesis, a plant hormone needed for cell elongation. A third mode of action involves the regulation of auxin activity and transport, and a fourth mode involves killing terminal buds and thus reducing apical dominance.
Gibberellin synthesis inhibitors are known which act at different sites in the biosynthetic pathway of gibberellins. Agents which act relatively late in the synthetic pathway are known as Class A gibberellin biosynthesis inhibitors. Trinexepac-ethyl is one such Class A agent, and is sold under the trade name Primo. Class B gibberellin biosynthesis inhibitors act relatively early in the gibberellin biosynthesis pathway. The compounds paclobutratzole and flurprimidol are known Class B gibberellin biosynthesis inhibitors and are sold under the trade names Trimmit and Cutless, respectively.
Growth regulation of turfgrass and other plants using high application rates may result in a significant waste of material, increased cost of application, and the discharge of excess plant growth regulator chemistry into the surrounding environment.
Gibberellin biosynthesis inhibitors have been used individually for some time in the management of turfgrasses such as those occurring on golf courses. Nonetheless, there remain needs for improved turfgrass and other plant management aspects which provide more effective results and/or which require lesser amounts of active agents. The present invention is addressed to these needs.